Pseudomonas aeruginosa, an opportunistic gram-negative bacterial pathogen found in most environments including water reservoirs and soil, is one of the leading nosocomial pathogen worldwide. This Gram-negative bacterium is best known for being the leading cause of morbidity and mortality in cystic fibrosis (CF) patients, with 80% of adult CF patients carrying P. aeruginosa in their lungs [1], and has recently gained notoriety by being classified as a ‘superbug’ by the media. The latter emanates from the intrinsic resistance that this opportunistic pathogen has against antibiotics [2], and its prominence as a cause of nosocomial infections (i.e. there are an estimated 10.000 cases each year in UK hospitals) [3].
Despite considerable advances in antimicrobial therapy, effective treatment and control of P. aeruginosa infections remains a persistent problem, primarily because of the natural resistance of the organism and its remarkable ability to acquire resistance to multiple antimicrobial agents by various mechanisms.
A vaccine against P. aeruginosa has long been sought after, but is so far not available. Several vaccine candidates have been assessed in experimental animals and humans, which include sub-cellular fractions, capsule components, purified and recombinant proteins.
Unique characteristics of the host and the pathogen have complicated the vaccine development.
Reference 4 reports a recombinant protein based vaccine approach on a single fusion polypeptide obtained by the fusion of two fragments of two outer membrane derived proteins, namely OprF and OprI. This vaccine is undergoing clinical trials [5], and further details are disclosed in ref 6.
Thus there remains a need to identify further and improved antigens for use as single antigens or in combinations in P. aeruginosa vaccines, and in particular for vaccines which are useful against multiple P. aeruginosa pathologies, comprising e.g. cystic fibrosis. Summing up, there is still the need to obtain an effective vaccine against P. aeruginosa. 